Hand held power tool with duplex handle

ABSTRACT

A hand held power tool, for example a chain saw is provided with a transversely extending front handle and with a second handle which extends over the top of the power unit of the tool in a fore-and-aft direction. The fore-and-aft handle is provided with a forward hand grip portion located approximately above the center of gravity of the power tool and a rearward hand grip portion located at the rear of the power unit. An independently operable trigger member controlling the engine throttle is provided for each hand grip portion so that the engine can be controlled by an operator gripping either hand grip portion of the fore-and-aft handle. Moreover, a choke valve operating member is provided adjacent the forward hand grip portion while an onoff switch is located below a median portion of the fore-and-aft handle in position to be operated by an operator holding the tool by either hand grip portion.

United States Patent [191 Green et a1.

1451 Oct. 29, 1974 Primary Examiner-Frank L. Abbott AssistantExaminer-William F. Pate, Ill Attorney, Agent, or FirmRobert 1E. Burns;Emmanuel J. Lobato; Bruce L. Adams 5 7 ABSTRACT A hand held power tool,for example a chain saw is provided with a transversely extending fronthandle and with a second handle which extends over the top of the powerunit of the tool in a fore-and-aft direction. The fore-and-aft handle isprovided with a forward hand grip portion located approximately abovethe center of gravity of the power tool and a rearward hand grip portionlocated at the rear of the power unit. An independently operable triggermember controlling the engine throttle is provided for each hand gripportion so that the engine can be controlled by an operator grippingeither hand grip portion of the foreand-aft handle. Moreover, a chokevalve operating member is provided adjacent the forward hand gripportion while an on-off switch is located below a median portion of thefore-and-aft handle in position to be operated by an operator holdingthe tool by either hand grip portion.

18 Claims, 12 Drawing Figures HAND HELD POWER TOOL WITH DUPLEX HANDLEFIELD OF INVENTION The present invention relates to hand held powertools and is especially applicable to chain saws. In particular itrelates to novel means for holding and controlling such power tools in aconvenient and safe manner.

BACKGROUND OF INVENTION Heretofore, a hand held power tool such as achain saw has customarily been provided with a front handle located atthe forward part of the power unit and extending transversely of thefore-aft axis of the unit and a rear handle located at the rear of thepower unit and usually of a pistol grip" configuration. The power toolis held and manipulated by gripping the front handle with one hand andthe rear handle with the other. The,

desirable to have one hand in position to operate the throttle triggeras soon as the engine starts. However, it is not convenient to hold thepower unit down by the rear handle since the location of the rear handlemakes it difficult to counteract the pull of the starter cord. If theunit is held by the front handle or by some other part of the powerunit, it is not possible immediately to operate the throttle triggerwhen the engine starts. Moreover, since the front handle is customarilylocated approximately over the center of gravity of the power tool, thehand holding the front handle must take almost all of the weight of thetool. In some circumstances however. it is desirable for the two handsof the operator to share the weight of the power tool so that one doesnot become overly tired. This cannot be done with the priorconstruction.

SUMMARY OF INVENTION It is an object of the present invention to providemeans for holding, manipulating and controlling hand held power tools ina manner which is more convenient and safer than with power tools ofprior construction. In accordance with the invention an elongate handlewhich extends over the power unit in a fore-and-aft direction and islocated approximately in the median vertical plane of the unit when innormal upright position is provided with a forward hand grip portionwhich lies approximately over the center of gravity of the power tooland a rearward hand grip portion located at the rear ofthe power unit.Moreover, each of the hand grip portions is provided with individuallyoperable engine control means, for example a throttle operating trigger.Hence, the engine can be controlled when the handle is held by theforward hand grip portion and can likewise be controlled when the handleis held by the rearward hand grip portion. The power unit is alsoprovided with a transversely extending handle located near the front endof the power unit. The front handle is preferably of thewrap-around'type extending across the top and along at least one side ofthe power unit. The power tool is normally held with one hand grippingthe front handle and the other hand gripping either the front hand gripportion or the rear hand grip portion of the handle that extends in afore-and-aft direction over the power unit. When the engine is beingstarted, the power tool is conveniently held with one hand gripping theforward hand grip portion of the fore-and-aft handle while the startercord is being pulled with the other hand. The engine is preferablyprovided with a choke valve operable by a member located adjacent theforward hand grip portion so that an operator holding the power tool bythe forward hand grip portion has accessible to him both the chokecontrol and throttle control of the engine. The engine is preferablyalso provided with an on-off switch which is located on top of theeasing below a median portion of the fore-aft handle so that it can beactuated from either hand grip portion. This provides the safety featurethat the engine can be turned off quickly by the operator regardless ofwhether he is holding the power tool by the forward hand grip portion orby the rearward hand grip portion.

BRIEF DESCRIPTION OF DRAWINGS Further characteristics, objects andadvantages of the invention will appear from the following descriptionof a preferred embodiment shown by way of example in the accompanyingdrawings in which:

FIG. 1 is a side view partially in longitudinal section of a chain sawembodying the invention;

FIG. 2 is a side view of a portion of the fore-aft handle of the chainsaw;

FIG. 3 is a plan view of the power unit of the chain saw with portionsbroken away to show internal construction;

FIG. 4 is a front view of the power unit with portions broken away;

FIGS. 5, 6, 7, 8 and 9 are cross sections through the fore-aft handletaken respectively on the lines 5--5, 6--6, 7-7, 8-8 and 9-9 in FIG. 1;

FIG. 10 is a perspective view of a lever forming a part of theconnections between the engine and engine control means on the fore-afthandle; and

FIGS. 11 and 12 are perspective views of motor control trigger memberslocated respectively at the forward hand grip portion and rearward handgrip portion of the fore-aft handle.

DESCRIPTION OF PREFERRED EMBODIMENT In the drawings there is shown bywayof example a chain saw havinga power unit 1 comprising an internalcombustion engine housed in a casing 2. The casing is shown as beingformed of two moldings or castings 2a and 2b which are preferably formedof magnesium or aluminum and are secured together by a plurality ofbolts 3. At one side of the power unit there is provided a sprocket 4which is driven by the engine and drives a cutting chain running on aguide'bar or cutter bar 5 which projects forwardly from the power unit.The driving sprocket 4 is shown protected by a guard 6. At

the opposite side of the power unit there is a fan and starter assembly7 comprising a fan which is mounted on the engine crank shaft and drawsair in through an annular grill 8 to cool the engine and a rewindstarter having a cord provided with a handle 9 which is pulled to turnthe engine over to start it. In addition to housing the engine and itsaccessories, the casing 2 contains reservoirs for fuel and for oil forlubricating the guide bar and chain. These reservoirs are filled throughopenings closed by removable caps 11 and 12. At the front of the casingthere are provided one or more spikes 13 which are engageable with thetrunk of a tree or a log that is being cut by the chain saw to assist infeeding the cutter. bar through the work. i

To provide for hand holding and manipulating the chain saw, the powerunit is provided with two handles 15 and 20. The first handle 15 islocated near the forward end of the power unit and is disposed at leastgenerally in a transverse plane perpendicular to the foreaft axis of thepower unit and located approximately at or somewhat in front of thecenter of gravity of the saw including the power unit, cutter bar andchain. It is shown as comprising a piece of tubing which is bent to forman upper approximately horizontal portion 15a disposed above the forwardportion of the power unit, an approximately vertical portion 15b whichis spaced from one side of the power unit and an inturned lower portion150 which fits over a projection 16 of the casing and is secured by ascrew 17. The upper end of the handle l5.fits over a projection 18 onthe side of a forward portion of the handle 20 and is secured by a screw19.

The second handle 20 extends in a generally foreand-aft direction overthe engine. It is shown as comprising a portion 20a which extendsupwardly and rearwardly from a lower rear portion of the casing 2 and aportion 20b which is curved and extends forwardly to the front portionof the power unit. As seen in FIGS. 3 and 4, the handle 20 is locatedapproximately midway between the opposite sides of the power unit and isthus disposed generally in the median vertical fore-aft plane of theunit. The portion 20b of the handle extending over the power unit iscontoured to provide a forward hand grip portion 21 occupyingapproximately the forward half of the handle portion 20b and a rearwardhand grip portion 22 occupying approximately the rearward half. As seenin the drawings, the cross sectional shape and dimensions of the handleare varied so as to define the two hand grip portions in such mannerthan an operator naturally grips the handle by one or the other handgrip portion and can tell by the feel of the handle that his hand is inthe desired position. Moreover, a downward protuberance 23 at the backof the forward hand grip portion 21 and a downward curve 24 ofthe handleat the rear of the rearward hand grip portion assists an operator inproperly positioning his hand by feel.

The fore-aft handle 20 is hollow and is shown in the drawings ascomprising in cross section a lower portion 25 which is of upwardlyopening channel cross section and a removable cover 26 which is ofdownwardly opening channel cross section. The lower portion 25 of thehandle is integral with the casing 2, being formed as a portion of thesame molding or casting that forms the casing part 2a. The upper portionor cover 26 is removable and is conveniently formed as a plasticmolding. The cover 26 and lower channel portion 25 fit together as shownin the cross sectional FIGS. 5 to 9. The cover 26 is removably held inplace by integral downwardly extending hook portions 26a of the coverwhich fit under a portion 27 at the forward portion of the easing and anintegral downwardly extending hook portion 26b at the rear of the coverwhich fits under a portion 28 at the rear of the handle. An opening 29at the rear of the handle provides access for insertion of a tool toengage the hook portion 26b to disengage it from the portion 28 andthereby release the cover 26 for removal. The material from which thecover is made is sufficiently resilient to permit flexing to engage thehook portion 2612 with, and to disengage it from, the portion 28 of thehandle.

Each of the hand grip portions of the fore-aft handle 20 is providedwith means for controlling the engine of the power unit. The power unitis illustrated as comprising a two cycle internal combustion enginehaving a carburetor 30. The carburetor has a throttle valve controlledby an arm 31. The engine throttle is controllable by a trigger member 32in the forward hand grip portion 21 and is independently controllable bya trigger member 33 in the rearward hand grip portion 22. Theconnections between the trigger members and the throttle comprise alever 34 which is pivotally mounted in the forward portion of the handle20 and has an arm connected with the throttle lever 31 by a link 35. Thetrigger member 32 of the forward hand grip portion 21 is slidably guidedfor upward movement in the handle and has a lateral projection 32a whichis engageable with an arm on the lever 34 to rotate the lever in acounterclockwise direction when the trigger member 32 is moved upwardly.This movement of the lever 34, transmitted through the link 35, movesthe throttle lever 31 in a direction to open the throttle. The triggermember 33 of the rearward hand grip portion 22 is pivotally mounted forrotary movement in a counterclockwise direction from the rest positionshown in FIG. 2 and has an arm engageable with an abutment on aconnecting rod 36 having a forward end portion engageable with an arm ofthe lever 34. When the trigger 33 is moved in a counterclockwisedirection, the connecting rod 36 moves forwardly and presses on an armof the lever 34 to swing the lever in a counterclockwise direction andthereby move the throttle toward open position. The throttle member 32of the forward hand grip portion is normally held in the rest positionshown in FIG. 1 by gravity and by the return spring (not shown) of thethrottle acting through the connecting link 35 and lever 34. Thethrottle member 33 of the rearward hand grip portion 22 is normally heldin rest position by gravity and by a spring 37, one end of which bearson a support 38 in the handle while the other end acts on the trigger 33to move it in a clockwise direction. With the arrangement shown, theengine throttle can be actuated independently either by the triggermember 32 of the forward hand grip portion 21 or the trigger member 33of the hand grip portion 22 while the other trigger remains in restposition.

The lever 34 is shown in more detail in FIG. 10. The lever is pivotallymounted in the handle by means of integral trunnion portions 34a whichproject from opposite sides of the lever and are received in socketportions 40 provided in the lower part 25 of the fore-aft handle. Thetrunnion portions 34a of the lever 34 are held in the socket portions 40by portions 41 which project downwardly from the handle cover 26. Hencethe lever 34 can be assembled merely by dropping it into the lowerportion of the handle so that the trunnions 34a rest in the sockets 34and then securing the cover 26 in place. The lever 34 has an arm 34bwhich is provided at its end with a hole 340 for receiving the link 35which is preferably formed of a suitably bent wire. An upwardlyprojecting second arm 34d is provided with a socket (FIG. 1) flanked byweb portions 342 to receive the forward end of the connecting rod 36. Arearward projection 34f constituting in effect a third arm of the leveris engageable by the projection 32a of the trigger 32 so as to turn thelever 34 in a counterclockwise direction when the trigger is movedupwardly.

The trigger 32 of the forward hand grip portion 21 is shown in moredetail in FIG. 11. It will be seen to be generally rectangular in shapewith a concave lower end portion 32b for engagement by a finger of theoperators hand to move the trigger upwardly. The above mentionedprojection 32a extends approximately perpendicularly from the forwardside edge of the trigger member in position to be engageable with thearm 34f of the lever 34. The upper portion of the trigger member isbifurcated by a slot 320 extending in a fore-andaft direction tostraddle the connecting rod 36. The trigger 32 extends down through aslot in the lower handle portion and its downward movement is limited byengagement of laterally enlarged portions 32d with the bottom part 25 ofthe handle on opposite sides of the slot. The trigger 32 is guided by anupstanding portion 42 in the lower part of the handle and is assembledmerely by dropping it into place before the connecting rod 36 isinstalled.

The connecting rod 36 is a straight length of wire or rod which isreceived in slots in the upstanding portions 38 and 42 of the lower part25 of the handle. It is re tained by downwardly projecting portions 43and 44 of the cover 26, the lower portions of which are bifurcated toreceive the rod. Hence, the rod can be assembled merely by dropping itinto the lower portion of the handle so as to be received in the slotsof portions 38 and 42 and then securing the cover 26 in place. Theconnecting rod 36 is provided near its rear end with an abutment whichis shown as being provided by a washer 36a which is secured to the rod,for example by welding or brazing.

The trigger member 33 of the rearward hand grip portion 22 is shown inmore detail in FIG. 12. It is provided at opposite sides with laterallyprojecting integral trunnions 33a which are received in sockets 45 inthe lower part 25 of the handle (FIG. 5). The trunnions 33a of thetrigger member 33 are retained in the sockets 45 by downwardlyprojecting portions 46 of the cover. Hence the trigger can be assembledmerely by dropping it into place and then applying the cover 26. Anupwardly projecting arm 33!) is bifurcated to straddle the rear endportion of the connecting rod 36 and engage the washer 36a secured onthe rod. The rear end of the spring 37 bears on the washer 36a and henceacts through the washer to bias the trigger in a clockwise direction.Rotation in a clockwise direction is limited by a projection 330 whichis engageable with the bottom of the handle. In rest position, a portionof the trigger extends down through a slot in the handle in position tobe engaged by a finger of the operators hand when gripping the rearwardhand grip portion 22.

In assembling the parts in the handle, the trigger members 32 and 33 andthe lever 34 are positioned in the lower part 25 ofthe handle asdescribed above. The connecting rod 36 with the spring 37 thereon isthen placed in position and the cover 26 is then secured in place,thereby likewise securing the trigger members, lever and connecting rod.The assembly of the parts is thereby made extremely simple andinexpensive.

The throttle is also provided with a customary choke valve operable byan arm 50 which extends through an opening in the top of the casing andis located in the vicinity of the forward hand grip portion 21. Hence,an operator hodlding the chain saw by the forward hand grip portion caneasily and conveniently actuate both the trigger 32 controlling thethrottle and the arm 50 controlling the choke valve of the carburetor.

The engine is also shown provided with an on-off switch 51 in theignition circuit. The switch must be in on position in order for theengine to be started and run. Hence, the engine can be quickly stoppedby moving the switch to off" position. The switch 51 is mounted on thetop of the casing below and slightly to one side of the handle 20 at aposition about the middle of the handle and hence approximately betweenthe forward and rearward hand grip portions. It can hence be operated bya finger of the operators hand when gripping either the forward or therearward hand grip portion of the handle. Hence, in case of need, theengine can be stopped quickly regardless of which hand grip portion isbeing used by the operator.

The forward hand grip portion 21 is located approximately above thecenter of gravity of the chain saw so than an operator can support allor most of the weight of the chain saw with one hand gripping theforward hand grip portion of the fore-aft handle. Thus the saw canconveniently be carried with one hand. The length of the handle betweenthe two triggers is sufficient that the saw can be held firmly by theforward hand grip portion without actuating either trigger. For sometypes of cutting, an operator can hold the forward hand grip portion 21of the fore-aft handle with his right hand while gripping the transversehandle 15 with his left hand to assist in guiding and controlling thesaw. Moreover, when starting the engine, it is convenient to hold thesaw on the ground or other suitable support by grip ping the forwardhand gripportion with the right hand while pulling the starter cord bymeans of the handle 9 with the left hand. With his right hand in thisposition, the operator can control the choke valve by means of the arm50 and the throttle valve by means of the forward trigger member 32. Hecan also conveniently manipulate the on-off switch 51. For other typesof cutting it is convenient to hold the saw with the right hand grippingthe rearward hand grip portion 22 while the left hand grips thetransverse handle 15. By having his right hand on the rear hand gripportion 22 at the rear of the power unit, an operator has more leverageto pivot the saw about the spikes 13 engaging a side of a log or tree tofeed the cutter bar into the work. When the saw is held in this mannerthe weight of the saw is distributed between the transverse handle 15located somewhat forwardly of the center of gravity of the saw and therear hand grip portion 22 located at the rear of the power unit. The sawis controlled by the rear trigger member 33.

It will thus be seen that the construction in accordance with thepresent invention provides means for holding, manipulating andcontrolling a chain saw or other hand held power tool in a convenientand safe manner. The manner in which the power tool is held can bevaried according to the wishes of the operator in order to hold the toolin the best manner for each particular operating condition. Moreover,changing the manner in which the tool is held from time to time ishelpful in avoiding operator fatigue. Whether the tool is held by theforward hand grip portion or the rearward hand grip portion, theoperator has full control of its operation and can, moreover, stop theengine quickly in the event'of an emergency.

While a preferred embodiment of the invention has been illustrated inthe drawings and is herein particularly described, it will be understoodthat the invention is in no way limited to this embodiment and that manymodifications and variations in construction can be made while retainingthe overall configuration.

What we claim and desire to secure by Letters Patent is:

1. In a hand held power tool comprising a power unit having a front anda rear, said power unit comprising a casing and a motor in the casingand having speed control means, and a tool unit disposed at the front ofthe power unit and driven by said power unit, means for manually holdingand controlling said power tool comprising a first handle disposedtransversely at the front of the power unit and a second handleextending over the power unit from the rear toward the front thereof,said second handle having two separate hand grip portions arranged intandem, namely a forward hand grip portion comprising a forward portionof said second handle and located approximately over the center ofgravity of the power tool and a rearward hand grip portion comprising aseparate rearward portion of said second handle and located whollyrearwardly of said forward hand grip portion and rearwardly of thecenter of gravity of the power tool, first motor control means at theforward end of the forward hand grip portion of said second handle inposition to be digitally operated by an operator holding said forwardhand grip portion, second motor control means forward of the rearwardhand grip portion of said second handle in position to be digitallyoperated by an operator holding said rearward hand grip portion, saidsecond motor control means being located between said forward hand gripportion and said rearward hand grip portion and means connecting saidfirst and second motor control means with said second control means ofthe motor, whereby said motor can be controlled by an operator holdingsaid second handle by either said forward hand grip portion or saidrearward hand grip portion.

2. A power tool according to claim 1, wherein said second handle iscontoured to define said forward and rearward hand grip portions so thatan operator can properly position his hand on one or the other of saidhand grip portions by feel.

3. A power tool according to claim 1, wherein said second handle extendsrearwardly beyond the rear of the casing.

4. A power tool according to claim 1, wherein said second handle ishollow and said connecting means is disposed in part in said hollowhandle.

5. A power tool according to claim 4, wherein said second handlecomprises a lower portion which is integral with said casing and a coverremovable secured on said lower portion.

6. A power tool according to claim 5, wherein said cover is moldedplastic material and is provided at opposite ends with integral hookingportions which hook onto said lower portion to secure the cover.

7. A power tool according to claim 5, wherein said second motor controlmeans comprises a trigger having a pivot portion, and wherein said lowerportion of the second handle has means for receiving said pivot portionto pivotally support said trigger and said cover has means for retainingsaid pivot portion in said receiving means whereby said trigger can beassembled merely by dropping it into the lower portion of said secondhandle and thereafter securing said cover in place.

8. A power tool according to claim 7, wherein said connecting meanscomprises a connecting rod extending forwardly in said second handlefrom said trigger, said lower portion and cover of said second handlehaving cooperating means for guiding said connecting rod, whereby saidconnecting rod can be assembled by dropping it into said lower portionand thereafter securing said cover in place.

9. A power tool according to claim 8, wherein said first motor controlmeans comprises a movable trigger, and wherein said connecting meansfurther comprises a pivoted lever having a portion engageable by saidconnecting rod, a portion engageable with said trigger of the forwardhand grip portion and a portion connected with said speed control meansof the motor, said lower portion of the second handle having means forguiding said last mentioned trigger and for pivotally supporting saidlever, whereby said last mentioned trigger and lever can be assembled bydropping them into said lower portion of the second handle andthereafter securing said cover in place.

10. A power tool according to claim 4, wherein said first motor controlmeans comprises a first trigger movably mounted in said second handleand having a rest position in which a portion thereof extends below saidsecond handle at the forward end of said forward hand grip portion, andsaid second motor control means comprises a second trigger movablymounted in said second handle and having a rest position in which aportion thereof extends below said second handle at the forward end ofsaid rearward hand grip portion.

11. A power tool according to claim 10, wherein said connecting meanscomprises means operably connecting both of said triggers to said motorspeed control means for operation of said speed control means by eitherone of said triggers while the other of said triggers remains in itsrest position.

12. A power tool according to claim 11, wherein said connecting meanscomprises a lever pivotally mounted at the front of said second handle,means connecting said lever with said motor speed control means, saidlever having a portion engageable by said first trigger to pivot saidlever in a direction to operate said speed control means and aconnecting rod in said hollow handle and movable by said second trigger,said rod being engageable with a portion of said lever to pivot saidlever in a direction to operate said speed control means.

13. A power tool according to claim 1, wherein said motor is an internalcombustion engine and said speed control means comprises a carburetorhaving a throttle to which said connecting means is connected.

14. A power tool according to claim 13, wherein said carburetor has achoke valve and a choke valve operating member located adjacent saidforward hand grip portion of said second handle in position to bedigitally operated by an operator holding said forward handle portion.

15. A power tool according to claim 13, wherein said engine has anon-off switch located at the top of said casing below a median portionof said second handle in position where it can be actuated by anoperator holdmg said second handle b i h id f rw d or aid dle isconnected to a lower rear portion of said casing. rearward hand gripportion.

16. A power tool according to claim 1, wherein said 18. A power unitaccording to claim 1, wherein said first handle Comprises a tubularhandle disposed generpower tool is a chain saw and has a cutter barextending in a Plane perpefldicular to a f the forwardly from said powerunit and spikes on the front power unit and having an approximatelyhorizontal of Said casin g in position to be engageable with the upperportion above the forward portion of the power unit and an approximatelyvertical side portion at one work whereby Y' secqnd handle whgn held byid f h power unit rearward hand grip portion affords leverage to pivot17 A power i according to claim 1 h i one said chain saw about saidspikes in engagement with the end of said first handle is connected tosecond handle Work and thereby move Said Cutter bar into the Workat itsforward end and the opposite end of said first han-

1. In a hand held power tool comprising a power unit having a front anda rear, said power unit comprising a casing and a motor in the casingand having speed control means, and a tool unit disposed at the front ofthe power unit and driven by said power unit, means for manually holdingand controlling said power tool comprising a first handle disposedtransversely at the front of the power unit and a second handleextending over the power unit from the rear toward the front thereof,said second handle having two separate hand grip portions arranged intandem, namely a forward hand grip portion comprising a forward portionof said second handle and located approximately over the center ofgravity of the power tool and a rearward hand grip portion comprising aseparate rearward portion of said second handle and located whollyrearwardly of said forward hand grip portion and rearwardly of thecenter of gravity of the power tool, first motor control means at theforward end of the forward hand grip portion of said second handle inposition to be digitally operated by an operator holding said forwardhand grip portion, second motor control means forward of the rearwardhand grip portion of said second handle in position to be digitallyoperated by an operator holding said rearward hand grip portion, saidsecond motor control means being located between said forward hand gripportion and said rearward hand grip portion and means connecting saidfirst and second motor control means with said second control means ofthe motor, whereby said motor can be controlled by an operator holdingsaid second handle by either said forward hand grip portion or saidrearward hand grip portion.
 2. A power tool according to claim 1,wherein said second handle is contoured to define said forward andrearward hand grip portions so that an operator can properly positionhis hand on one or the other of said hand grip portions by feel.
 3. Apower tool according to claim 1, wherein said second handle extendsrearwardly beyond the rear of the casing.
 4. A power tool according toclaim 1, wherein said second handle is hollow and said connecting meansis disposed in part in said hollow handle.
 5. A power tool according toclaim 4, wherein said second handle comprises a lower portion which isintegral with said casing and a cover removable secured on said lowerportion.
 6. A power tool according to claim 5, wherein said cover ismolded plastic material and is provided at opposite ends with integralhooking portions which hook onto said lower portion to secure the cover.7. A power tool according to claim 5, wherein said second motor controlmeans comprises a trigger having a pivot portion, and wherein said lowerportion of the second handle has means for receiving said pivot portionto pivotally support said trigger and said cover has means for retainingsaid pivot portion in said receiving means whereby said trigger can beassembled merely by dropping it into the lower portion of said secondhandle and thereafter securing said cover in place.
 8. A power toolaccording to claim 7, wherein said connecting means comprises aconnecting rod extending forwardly in said second handle from saidtrigger, said lower portion and cover of said second handle havingcooperating means for guiding said connecting rod, whereby saidconnecting rod can be assembled by dropping it into said lower portionand thereafter securing said cover in place.
 9. A power tool accordingto claim 8, wherein said first motor control means comprises a movabletrigger, and wherein said connecting means further comprises a pivotedlever having a portion engageable by said connecting rod, a portionengageable with said trigger of the forward hand grip portion and aportion connected with said speed control means of the motor, said lowerportion of the second handle having means for guiding said lastmentioned trigger and for pivotally supporting said lever, whereby saidlast mentioned trigger and lever can be assembled by dropping them intosaid lower portion of the second handle and thereafter securing saidcover in place.
 10. A power tool according to claim 4, wherein saidfirst motor control means comprises a first trigger movably mounted insaid second handle and having a rest position in which a portion thereofextends below said second handle at the forward end of said forward handgrip portion, and said second motor control means comprises a secondtrigger movably mounted in said second handle and having a rest positionin which a portion thereof extends below said second handle at theforward end of said rearward hand grip portion.
 11. A power toolaccording to claim 10, wherein said connecting means comprises meansoperably connecting both of said triggers to said motor speed controlmeans for operation of said speed control means by either one of saidtriggers while the other of said triggers remains in its rest position.12. A power tool according to claim 11, wherein said connecting meanscomprises a lever pivotally mounted at the front of said second handle,means connecting said lever with said motor speed control means, saidlever having a portion engageable by said first trigger to pivot saidlever in a direction to operate said speed control means and aconnecting rod in said hollow handle and movable by said second trigger,said rod being engageable with a portion of said lever to pivot saidlever in a direction to operate said speed control means.
 13. A powertool according to claim 1, wherein said motor is an internal combustionengine and said speed control means comprises a carburetor having athrottle to which said connecting means is connected.
 14. A power toolaccording to claim 13, wherein said carburetor has a choke valve and achoke valve operating member located adjacent said forward hand gripportion of said second handle in position to be digitally operated by anoperator holding said forward handle portion.
 15. A power tool accordingto claim 13, wherein said engine has an on-off switch located at the topof said casing below a median portion of said second handle in positionwhere it can be actuated by an operator holding said second handle byeither said forward or said rearward hand grip portion.
 16. A power toolaccording to claim 1, wherein said first handle comprises a tubularhandle disposed generally in a plane perpendicular to a fore-aft axis ofthe power unit and having an approximately horizontal upper portionabove the forward portion of the power unit and an approximatelyvertical side portion at one side of the power unit.
 17. A power unitaccording to claim 16, wherein one end of said first handle is connectedto second handle at its forward end and the opposite end of said firsthandle is connected to a lower rear portion of said casing.
 18. A powerunit according to claim 1, wherein said power tool is a chain saw andhas a cutter bar extending forwardly from said power unit and spikes onthe front of said casing in position to be engageable with the work,whereby said second handle when held by the rearward hand grip portionaffords leverage to pivot said chain saw about said spikes in engagementwith the work and thereby move said cutter bar into the work.